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Home >> Mazda >> 2017 >> MX-5 Miata Club, Automatic Trans >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Body Control System (BCM) >> Body Control Module (BCM) Inspection
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Body Control Module (BCM) Inspection

  1. Disconnect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION ).
  2. Remove the scuff plate (driver's side). (See SCUFF PLATE REMOVAL/INSTALLATION ).
  3. Remove the front side trim (driver's side). (See FRONT SIDE TRIM REMOVAL/INSTALLATION ).
  4. Remove the BCM. (See BODY CONTROL MODULE (BCM) REMOVAL/INSTALLATION ).
  5. Connect the BCM connector.
  6. Connect the negative battery cable. (See NEGATIVE BATTERY CABLE DISCONNECTION/CONNECTION ).
  7. Verify that the voltages of each of the terminals are as indicated in the terminal voltage table (reference). (See Terminal Voltage Table (Reference) ).
Fig 1: Identifying BCM Wiring Harness Side Connector Terminals
G11274619Courtesy of MAZDA MOTORS CORP.
TERMINAL VOLTAGE REFERENCE

Terminal Signal Connected to Measurement condition Voltage (V) Inspection item(s)
1A Power supply HAZARD 15 A fuse Under any condition B+ HAZARD 15 A fuse
1B Power supply
  • ROOM 25 A fuse
  • INTERIOR 15 A fuse
 Under any condition B+
  • ROOM 25 A fuse
  • INTERIOR 15 A fuse
1C - - - - -
1D - - - - -
1E Rear turn light (RH) control Rear turn light (RH) Ignition is switched ON (engine off or on) Turn switch is in right turn position 1.0 or less ↔ B+ Rear turn light (RH)
Turn switch is in position other than above 1.0 or less
1F - - - - -
1G Rear turn light (LH) control Rear turn light (LH) Ignition is switched ON (engine off or on) Turn switch is in left turn position 1.0 or less ↔ B+ Rear turn light (LH)
Turn switch is in position other than above 1.0 or less
1H Interior light power supply Map light Under any condition B+ Map light
1I - - - - -
1J - - - - -
1K Ground Body ground Under any condition 1.0 or less Body ground
1L Ground Body ground Under any condition 1.0 or less Body ground
2A Lock input (door lock-link switch (driver's side)) Door latch and lock actuator (driver's side) Driver's door is locked 1.0 or less Door latch and lock actuator (driver's side)
Driver's door is unlock Approx. 10
2B Unlock input (door lock-link switch (driver's side)) Door latch and lock actuator (driver's side) Driver's door is locked Approx. 9.5 Door latch and lock actuator (driver's side)
Driver's door is unlocked 1.0 or less
2C CAN_L CAN system related module Terminal used for communication therefore determination based on terminal voltage is not possible.
2D CAN_H CAN system related module Terminal used for communication therefore determination based on terminal voltage is not possible.
2E Top lock switch signal Top lock switch Convertible top is open 1.0 or less Top lock switch
Convertible top is closed Approx. 9.5
2F - - - - -
2G Door latch switch (passenger's side) signal Door latch and lock actuator (passenger's side) Door (passenger's side) is open 1.0 or less Door latch and lock actuator (passenger's side)
Door (passenger's side) is closed Approx. 9.0
2H Door latch switch (driver's side) signal Door latch and lock actuator (driver's side) Door (driver's side) is open 1.0 or less Door latch and lock actuator (driver's side)
Door (driver's side) is closed Approx. 9.5
2I - - - - -
2J Serial communication Start stop unit Terminal used for communication therefore determination based on terminal voltage is not possible.
2K (1) Door lock switch signal Door lock switch (RH) Door lock switch is turned to unlock side (driver's side or passenger's side) 1.0 or less Door lock switch (RH)
Door lock switch is turned to lock side (driver's side or passenger's side) Approx. 1.25
Other Approx 5.0
2L Door key cylinder switch signal Door latch and lock actuator (driver's side) Door key cylinder is turned to unlock side 1.0 or less Door latch and lock actuator (driver's side)
Door key cylinder is turned to lock side Approx. 1.25
Other Approx 5.0
2M(2) Lock input (door lock-link switch (passenger's side)) Door latch and lock actuator (passenger's side) Passenger's door is unlocked 1.0 or less Door latch and lock actuator (passenger's side)
Passenger's door is locked B+
2N - - - - -
2O - - - - -
2P - - - - -
2Q Fuel sensor signal Fuel gauge sender unit Inspect fuel gauge sender unit and related wiring harness because determination based on terminal voltage is not possible.
(See FUEL GAUGE SENDER UNIT INSPECTION ).
2R Fuel sensor ground Fuel gauge sender unit Under any condition 1.0 or less Fuel gauge sender unit
2S Trunk lid unlatch switch signal (exterior) Trunk lid opener switch (exterior) Trunk is opened 1.0 or less Trunk lid opener switch (exterior)
Trunk is closed Approx. 4.5
2T - - - - -
2U - - - - -
2V - - - - -
2W - - - - -
2X - - - - -
2Y LIN communication Electrical supply unit (ESU) Terminal used for communication therefore determination based on terminal voltage is not possible.
2Z - - - - -
2AA - - - - -
2AB - - - - -
2AC Trunk lid latch switch signal Trunk lid latch and release actuator Trunk is opened 1.0 or less Trunk lid latch and release actuator
Trunk is closed Approx. 9.5
2AD - - - - -
2AE - - - - -
2AF - - - - -
3A Front turn light (RH) control Front turn light (RH) Ignition is switched ON (engine off or on) Turn switch is in right turn position 1.0 or less ↔ B+ Front turn light (RH)
Turn switch is in position other than above 1.0 or less
3B Front turn light (LH) control Front turn light (LH) Ignition is switched ON (engine off or on) Turn switch is in left turn position 1.0 or less ↔ B+ Front turn light (LH)
Turn switch is in position other than above 1.0 or less
3C CAN_H CAN system related module Terminal used for communication therefore determination based on terminal voltage is not possible.
3D CAN_L CAN system related module Terminal used for communication therefore determination based on terminal voltage is not possible.
3E Blower motor relay control
  • Blower relay
  • HEATER 40 A fuse
 Ignition is switched ON (engine off or on) Blower motor is operated using fan switch 1.0 or less
  • Blower relay
  • HEATER 40 A fuse
Blower motor is turned off by pressing climate control unit OFF button B+
3F Windshield wiper INT relay control Wiper INT relay Ignition is switched ON (engine off or on) Windshield wiper switch is in position other than OFF 1.0 or less Wiper INT relay
Windshield wiper switch is in OFF position B+
3G Windshield wiper motor (HI) control Wiper HI relay Ignition is switched ON (engine off or on) Windshield wiper switch is in HIGH position 1.0 or less Wiper HI relay
Windshield wiper switch is in OFF position B+
3H Horn relay control Horn relay Ignition is switched ON (engine off or on) Horn switch is on 1.0 or less Horn relay
Horn switch is off B+
3I - - - - -
3J - - - - -
3K Rear window defogger relay control Rear window defogger relay Ignition is switched ON (engine off or on) Rear window defogger switch is on 1.0 or less Rear window defogger relay
Rear window defogger switch is off B+
3L - - - - -
3M Autostop switch signal Wiper motor Ignition is switched ON (engine off or on) Wiper switch is on and wiper is operating 1.0 or less Wiper motor
Wiper switch is off B+
3N Power supply
  • ENG+B 7.5 A fuse
  • ROOM 25 A fuse
 Under any condition B+
  • ENG+B 7.5 A fuse
  • ROOM 25 A fuse
3O Ignition power supply METER1 10 A fuse Ignition is switched ON (engine off or on) B+ METER1 10 A fuse
The ignition is switched off (LOCK) 1.0 or less
3P - - - - -
3Q(3) Washer fluid level sensor signal Washer fluid level sensor Ignition is switched ON (engine off or on) Washer fluid level sensor is less than MIN (washer fluid level sensor on) 1.0 or less Washer fluid level sensor
Washer fluid level sensor is MIN or more (Washer fluid level sensor off) B+
3R Brake fluid level sensor signal Brake fluid level sensor Ignition is switched ON (engine off or on) Brake fluid level sensor is less than MIN (brake fluid level sensor on) 1.0 or less Brake fluid level sensor
Brake fluid level sensor is MIN or more (brake fluid level sensor off) B+
3S - - - - -
3T Horn switch control Horn switch Ignition is switched ON (engine off or on) Horn switch is on (long press) 1.0 or less Horn switch
Horn switch is off B+
3U Trunk unlatch switch signal (interior) Trunk lid opener switch (interior) Trunk lid opener switch (interior) is on (trunk lid opener switch (interior) is pressed) 1.0 or less Trunk lid opener switch (interior)
Trunk lid opener switch (interior) is off (trunk lid opener switch (interior) is not pressed) B+
3V - - - - -
3W (5) Hood latch switch signal Hood latch switch Hood is open Approx. 9.0 Hood latch switch
Hood is closed 1.0 or less
3X LIN communication Auto-light sensor/rain sensor (4) Terminal used for communication therefore determination based on terminal voltage is not possible.
(1) With door lock switch

(2) With front fog light

(3) With washer fluid level sensor

(4) With auto light system/auto wiper system

(5) With hood latch switch
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